/* SPDX-License-Identifier: GPL-2.0 */#ifndef _LINUX_COMPACTION_H#define _LINUX_COMPACTION_H /* * Determines how hard direct compaction should try to succeed. * Lower value means higher priority, analogically to reclaim priority. */enum compact_priority {	COMPACT_PRIO_SYNC_FULL,	MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL,	COMPACT_PRIO_SYNC_LIGHT,	MIN_COMPACT_COSTLY_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,	DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,	COMPACT_PRIO_ASYNC,	INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC}; /* Return values for compact_zone() and try_to_compact_pages() *//* When adding new states, please adjust include/trace/events/compaction.h */enum compact_result {	/* For more detailed tracepoint output - internal to compaction */	COMPACT_NOT_SUITABLE_ZONE,	/*	 * compaction didn't start as it was not possible or direct reclaim	 * was more suitable	 */	COMPACT_SKIPPED,	/* compaction didn't start as it was deferred due to past failures */	COMPACT_DEFERRED, 	/* compaction not active last round */	COMPACT_INACTIVE = COMPACT_DEFERRED, 	/* For more detailed tracepoint output - internal to compaction */	COMPACT_NO_SUITABLE_PAGE,	/* compaction should continue to another pageblock */	COMPACT_CONTINUE, 	/*	 * The full zone was compacted scanned but wasn't successfull to compact	 * suitable pages.	 */	COMPACT_COMPLETE,	/*	 * direct compaction has scanned part of the zone but wasn't successfull	 * to compact suitable pages.	 */	COMPACT_PARTIAL_SKIPPED, 	/* compaction terminated prematurely due to lock contentions */	COMPACT_CONTENDED, 	/*	 * direct compaction terminated after concluding that the allocation	 * should now succeed	 */	COMPACT_SUCCESS,}; struct alloc_context; /* in mm/internal.h */ /* * Number of free order-0 pages that should be available above given watermark * to make sure compaction has reasonable chance of not running out of free * pages that it needs to isolate as migration target during its work. */static inline unsigned long compact_gap(unsigned int order){	/*	 * Although all the isolations for migration are temporary, compaction	 * free scanner may have up to 1 << order pages on its list and then	 * try to split an (order - 1) free page. At that point, a gap of	 * 1 << order might not be enough, so it's safer to require twice that	 * amount. Note that the number of pages on the list is also	 * effectively limited by COMPACT_CLUSTER_MAX, as that's the maximum	 * that the migrate scanner can have isolated on migrate list, and free	 * scanner is only invoked when the number of isolated free pages is	 * lower than that. But it's not worth to complicate the formula here	 * as a bigger gap for higher orders than strictly necessary can also	 * improve chances of compaction success.	 */	return 2UL << order;} #ifdef CONFIG_COMPACTIONextern int sysctl_compact_memory;extern int sysctl_compaction_handler(struct ctl_table *table, int write,			void __user *buffer, size_t *length, loff_t *ppos);extern int sysctl_extfrag_threshold;extern int sysctl_compact_unevictable_allowed; extern int fragmentation_index(struct zone *zone, unsigned int order);extern enum compact_result try_to_compact_pages(gfp_t gfp_mask,		unsigned int order, unsigned int alloc_flags,		const struct alloc_context *ac, enum compact_priority prio,		struct page **page);extern void reset_isolation_suitable(pg_data_t *pgdat);extern enum compact_result compaction_suitable(struct zone *zone, int order,		unsigned int alloc_flags, int classzone_idx); extern void defer_compaction(struct zone *zone, int order);extern bool compaction_deferred(struct zone *zone, int order);extern void compaction_defer_reset(struct zone *zone, int order,				bool alloc_success);extern bool compaction_restarting(struct zone *zone, int order); /* Compaction has made some progress and retrying makes sense */static inline bool compaction_made_progress(enum compact_result result){	/*	 * Even though this might sound confusing this in fact tells us	 * that the compaction successfully isolated and migrated some	 * pageblocks.	 */	if (result == COMPACT_SUCCESS)		return true; 	return false;} /* Compaction has failed and it doesn't make much sense to keep retrying. */static inline bool compaction_failed(enum compact_result result){	/* All zones were scanned completely and still not result. */	if (result == COMPACT_COMPLETE)		return true; 	return false;} /* * Compaction  has backed off for some reason. It might be throttling or * lock contention. Retrying is still worthwhile. */static inline bool compaction_withdrawn(enum compact_result result){	/*	 * Compaction backed off due to watermark checks for order-0	 * so the regular reclaim has to try harder and reclaim something.	 */	if (result == COMPACT_SKIPPED)		return true; 	/*	 * If compaction is deferred for high-order allocations, it is	 * because sync compaction recently failed. If this is the case	 * and the caller requested a THP allocation, we do not want	 * to heavily disrupt the system, so we fail the allocation	 * instead of entering direct reclaim.	 */	if (result == COMPACT_DEFERRED)		return true; 	/*	 * If compaction in async mode encounters contention or blocks higher	 * priority task we back off early rather than cause stalls.	 */	if (result == COMPACT_CONTENDED)		return true; 	/*	 * Page scanners have met but we haven't scanned full zones so this	 * is a back off in fact.	 */	if (result == COMPACT_PARTIAL_SKIPPED)		return true; 	return false;}  bool compaction_zonelist_suitable(struct alloc_context *ac, int order,					int alloc_flags); extern int kcompactd_run(int nid);extern void kcompactd_stop(int nid);extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx); #elsestatic inline void reset_isolation_suitable(pg_data_t *pgdat){} static inline enum compact_result compaction_suitable(struct zone *zone, int order,					int alloc_flags, int classzone_idx){	return COMPACT_SKIPPED;} static inline void defer_compaction(struct zone *zone, int order){} static inline bool compaction_deferred(struct zone *zone, int order){	return true;} static inline bool compaction_made_progress(enum compact_result result){	return false;} static inline bool compaction_failed(enum compact_result result){	return false;} static inline bool compaction_withdrawn(enum compact_result result){	return true;} static inline int kcompactd_run(int nid){	return 0;}static inline void kcompactd_stop(int nid){} static inline void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx){} #endif /* CONFIG_COMPACTION */ struct node;#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)extern int compaction_register_node(struct node *node);extern void compaction_unregister_node(struct node *node); #else static inline int compaction_register_node(struct node *node){	return 0;} static inline void compaction_unregister_node(struct node *node){}#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */ #endif /* _LINUX_COMPACTION_H */